1979, a screaming 613KHz clock, killer graphics, and it's a Hewlett Packard, it doesn't get much better than this!Dave powers up the the classic HP85 Scientific / Engineering Professional Personal Computer and has a play around.

Thanks for doing this one, Dave. I have noticed one thing about computers today is that I don't really lust after them like I did back in the day. It's like there is such a homogenization of tech these days that today, it's all more or less the same. The sheer diversity and imagination and attention to detail of late 70's early 80's HP tech was just lust-worthy all by itself. And the manuals! The manuals were fantastic--actually worth reading!

Note for the unaware, HP BASIC was lightyears more useful than any other BASIC. No, it's not C++, but you could certainly do real work with it. You could very much make the best use of the small amount of memory you had via indirect calls, etc.

I repaired a HP-9100 for a collector a few years ago. These are the first programmable scientific calculators. You could see it a bit as the great-grandmother of the HP-85, it is more a calculator as a true computer. But the 85 is a bit the same I think.

If you can get your hands on one of those for a tear down then do it. They are aw-sum. Over 1800 diodes and over 500 transistors. The first teflon multilayer pcb to make the ROM, core memory etc. There is no service manual. I managed to repair one of the 3 he had. Two had broken CRT's. I got far with an other, using a round CRT I could fit more or less to see if I could get it working again before hunting down an original CRT, but it turned out to have a corrupt rom or something like that. There are no service manuals, only some schematics hand-drawn by a collector.

Nice video Dave! Thanks for that walk through memory lane. For me, it's personal since in my younger ( late 1970's) days I was an Applications Engineer for HP Canada in the 06 group responsible for supporting customers in Western Canada with their 9825, 9835 and 9845 desktop...."portable".... computers and peripherals. They truly were remarkably handy and amazing for the day. As you say...none of this iPad rubbish. BTW, I have an iPad pro and find it just as fun to use as I did writing HPL code on a 9835, albeit a different kind of "fun"

In the 1970's I gave numerous classes and met many customers that absolutely loved what these things could do. I also met Bill Hewlett and Dave Packard, in person, in Palo Alto during my "neophyte" training. How many engineers today can say that?

Somewhere in the 1980’s I have worked as a customer engineer at HP in the Netherlands. I still have some parts from these days. For instance your original 3/8Amp fuse with part number 1535-2586/7.HP used light bulbs for detecting the end of tape in the technical HP79xx series. Maybe the HP85 uses a light bulb too. If so, I can send you some original bulbs (part number 2140-0221).

EDITNew belts arrived. Picture showing the remains of the print head belt. Plan to measure one of my other DAT drives to get dimensions for the tape drive. Maybe there is something available that would work.

This brought back memories of another machine - the TRS-80. Specifically the Model I with 4K RAM and Level 1 Basic.

Many years ago when trading on Saturdays stopped at midday (or 1pm for radical shopkeepers) I was working for Tandy when they were brought in 3 units that were to tour the branches across Australia - before they would be offered for sale. Each store had one for 3 days and then it had to be sent to the next one.

It arrived on our doorstep on a Thursday morning and we had to deliver it to the next store first thing Monday. So it sat in the store being shown off and being played with until Saturday close. It then had a day and a half to find its way to the next stop - which just happened to be a minor detour for me. Since I had the interest in computers (the store manager didn't - aside from the money it could put in the till) and the trust of the Manager, I was allowed to provide the transport, with a word of caution to 'look after it'. So it came home with me on the Saturday and .....

Yes - I actually cleared my desk off completely and set it up in pride of place. Little else got done that weekend. Playing with this fascinating machine was absorbing - but it's limitations soon became a source of annoyance. A day and a half was enough to get a feel for it - and for me to know I would want something more.

It was duly delivered on the Monday, with everything in order - and the memory remains as one of those magical opportunities I was able to enjoy.

In those days, HP was a respected name among professionals. You could not get better than Hewlett Packard, except maybe some specialist stuff like W&G. It was like driving a high end Mercedes compared to a crappy Volkswagen. It was a respected name. Today, HP is a joke. After they merged with Compaq they are little more than a maker of low end consumer junk. Very sad that a company can lose so much respect.

I used on of these HP-85's back at RMIT when I was a student there. I loved those types of machines. I also used a graphical Nova which was championed by the famous Norbert Nimervoll in the EE department. And of course the Cyber 72 whose O/S was called KRONOS but was upgraded to a Cyber 73 running NOS.

In 1979 I bought my own computer, a Dick Smith System-80. It cost about a month's salary for a professional at the time. It came with 16K RAM, "pirated BIOS" from the TRS-80 and a whopping cassette drive interface.

Fully loaded with all options in 1978 .....$34795 CAD. I had a demo unit to lug around in the company car and had lots of fun with it when overnighting at a hotel before a seminar the next day.....except those rare times when an attractive woman was competing for my time.

Somewhere in the 1980’s I have worked as a customer engineer at HP in the Netherlands. I still have some parts from these days. For instance your original 3/8Amp fuse with part number 1535-2586/7.HP used light bulbs for detecting the end of tape in the technical HP79xx series. Maybe the HP85 uses a light bulb too. If so, I can send you some original bulbs (part number 2140-0221).

Let me know if you want me to send these parts.

I still have stacks of HP-85s, 86s, 87s, 87Ms, 9820s, 9825s, 9835s and 9845s, ONE HP 9831 and even a pair HP 9877 Mass Memory (Quad tape) drives. I even have one prototype HP-85 :-)

All of HPs (9825s, HP-85s, etc) that used that tape cassette used a physical hole on the tape to signal the EOT. But the problem is that the magnetic media flakes off of the (clear) tape and when that happens the calculator sees the clear spot and errors out with an "Unexpected End of Tape" message and the media is really, really, BAD about flaking off of those tapes! A few years ago I got an entire case of 100 (IIRC) brand new SEALED HP tapes and EVERY one of them was bad. I did find a few later tapes made by 3M that were the same size and I got a few of them to work but the HP tapes ALL went bad literally within a few days. I repaired a lot of those tape drives and I did have some success with getting them to work but I eventually gave up on getting them to work reliably due to the unreliability of the old tapes. If you really want to play with one of these old machines, get an HP-87 with the Mass Memory support, and HP-IB interface and connect it to one of the HP-IB 3 1/2" floppy drives. Those WORK! There ARE even some HP-IB hard drives that will work with them but it gets tricky finding a drive that uses the same command protocall that the old HP calculators use.

But FWIW my favorite of all the old HPs are the HP-120 and HP-125 64k CPM machines! Those little suckers work great with the 3 1/2" HP-IB floppy drives and are FAST!

Still got a pair of 9825's stashed away somewhere, the 16-bit processor a 3 chip hybrid was used in a few HP instruments, HP3585 is the only one I can think of at the moment. As far as I know the architecture was based on one of the HP 21xx series mini computers, HP2104 or 2114 maybe ? The assembler mnemonics are the same. By the way if anyone has a hex dump for the HP9825 assembler cartridge I would greatly appreciate a copy.